- ID:
- ivo://CDS.VizieR/III/232
- Title:
- STELIB: A library of stellar spectra at R~2000
- Short Name:
- III/232
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- STELIB is a new spectroscopic stellar library, available at http://webast.ast.obs-mip.fr/stelib . It consists in an homogeneous library of stellar spectra in the visible range (3200 to 9500){AA}), with an intermediate spectral resolution (<~3{AA}) and sampling (1{AA}), and corrected from interstellar absorption. This library includes 255 stars of various spectral types and luminosity classes, spanning a relatively wide range in metallicity. The spectral resolution, wavelength and spectral type coverage of this library represents a substantial improvement over previous libraries used in population synthesis models. The overall absolute photometric uncertainty is 3%. The data were obtained during two runs, one at the 1m Jacobus Kaptein Telescope (JKT), Roque de los Muchachos Observatory, La Palma, Canary Islands, Spain, between 1994 March 28 and April 4, and a second one at the 2.3m of the Australian National University at Siding Spring (SSO), Australia, between 1994 December 25 and 31.
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Search Results
- ID:
- ivo://CDS.VizieR/J/ApJ/891/23
- Title:
- Stellar abundances from LAMOST MRS (SPCAnet)
- Short Name:
- J/ApJ/891/23
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The fundamental stellar atmospheric parameters (Teff and logg) and 13 chemical abundances are derived for medium-resolution spectroscopy from Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST) Medium Resolution Survey (MRS) data sets with a deep-learning method. The neural networks we designed, named SPCANet, precisely map LAMOST MRS spectra to stellar parameters and chemical abundances. The stellar labels derived by SPCANet have precisions of 119K for Teff and 0.17dex for logg. The abundance precision of 11 elements including [C/H], [N/H], [O/H], [Mg/H], [Al/H], [Si/H], [S/H], [Ca/H], [Ti/H], [Cr/H], [Fe/H], and [Ni/H] are 0.06 {\sim} 0.12 dex, while that of [Cu/H] is 0.19dex. These precisions can be reached even for spectra with signal-to-noise ratios as low as 10. The results of SPCANet are consistent with those from other surveys such as APOGEE, GALAH, and RAVE, and are also validated with the previous literature values including clusters and field stars.
- ID:
- ivo://CDS.VizieR/J/A+A/552/A128
- Title:
- Stellar abundances of neutron-capture elements
- Short Name:
- J/A+A/552/A128
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The aim of this work is to present and discuss the observations of the iron peak (Fe, Ni) and neutron-capture element (Y, Zr, Ba, La, Ce, Nd, Sm, and Eu) abundances for 276 FGK dwarfs, located in the galactic disk with metallicity -1<[Fe/H]<+0.3. Atmospheric parameters and chemical composition of the studied stars were determined from an high resolution, high signal-to-noise echelle spectra obtained with the echelle spectrograph ELODIE at the Observatoire de Haute-Provence (France). Effective temperatures were estimated by the line depth ratio method and from the H{alpha} line-wing fitting. Surface gravities (logg) were determined by parallaxes and the ionization balance of iron. Abundance determinations were carried out using the LTE approach, taking the hyperfine structure for Eu into account, and the abundance of Ba was computed under the NLTE approximation. We are able to assign most of the stars in our sample to the substructures of the Galaxy thick disk, thin disk, or Hercules stream according to their kinematics. The classification of 27 stars is uncertain. For most of the stars in the sample, the abundances of neutron-capture elements have not been measured earlier. For all of them, we provide the chemical composition and discuss the contribution from different nucleosynthesis processes.
- ID:
- ivo://CDS.VizieR/J/A+A/552/A27
- Title:
- Stellar activity and kinematics of FGK stars
- Short Name:
- J/A+A/552/A27
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of a study of the stellar activity in the solar neighborhood using complete kinematics (galactocentric velocities U,V,W) and the chromospheric activity index log RHK. We analyzed the average activity level near the centers of known moving groups using a sample of 2529 stars and found that the stars near these associations tend to be more active than field stars. This supports the hypothesis that these structures, or at least the dominant fraction of them, are composed of kinematically bound, young stars. We confirmed our results by using Galaxy Evolution Explorer (GALEX) UV data and kinematics taken from the Geneva-Copenhagen Survey for the stars in the sample. Finally, we present a compiled catalog with kinematics and activities for 2529 stars and a list of potential moving group members selected based on their stellar activity level.
- ID:
- ivo://CDS.VizieR/J/A+AS/142/275
- Title:
- Stellar activity of late-type stars
- Short Name:
- J/A+AS/142/275
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results from a spectroscopic CaII H&K survey of 1058 late-type stars selected from a color-limited subsample of the Hipparcos (Cat. <I/239>) catalog. Out of these 1058 stars, 371 stars were found to show significant H&K emission, most of them previously unknown; 23% with strong emission, 36% with moderate emission, and 41% with weak emission. These spectra are used to determine absolute H&K emission-line fluxes, radial velocities, and equivalent widths of the luminosity-sensitive Sr II line at 4077{AA}. Red-wavelength spectroscopic and Stroemgren y photometric follow-up observations of the 371 stars with H&K emission are used to additionally determine the absolute H{alpha}-core flux, the lithium abundance from the Li I 6708{AA} equivalent width, the rotational velocity vsini, the radial velocity, and the light variations and its periodicity.
- ID:
- ivo://CDS.VizieR/J/AJ/160/214
- Title:
- 130 Stellar ages & planetary orbital properties
- Short Name:
- J/AJ/160/214
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Many exoplanets have orbital characteristics quite different from those seen in our own solar system, including planets locked in orbital resonances and planets on orbits that are elliptical or highly inclined from their host star's spin axis. It is debated whether the wide variety in system architecture is primarily due to differences in formation conditions (nature) or due to evolution over time (nurture). Identifying trends between planetary and stellar properties, including stellar age, can help distinguish between these competing theories and offer insights as to how planets form and evolve. However, it can be challenging to determine whether observed trends between planetary properties and stellar age are driven by the age of the system- pointing to evolution over time being an important factor-or other parameters to which the age may be related, such as stellar mass or stellar temperature. The situation is complicated further by the possibilities of selection biases, small number statistics, uncertainties in stellar age, and orbital evolution timescales that are typically much shorter than the range of observed ages. Here, we develop a Bayesian statistical framework to assess the robustness of such observed correlations and to determine whether they are indeed due to evolutionary processes, are more likely to reflect different formation scenarios, or are merely coincidental. We apply this framework to reported trends between stellar age and 2:1 orbital resonances, spin-orbit misalignments, and hot Jupiters' orbital eccentricities. We find strong support for the nurture hypothesis only in the final case.
- ID:
- ivo://CDS.VizieR/J/ApJS/127/39
- Title:
- Stellar and gas kinematics in early-type galaxies
- Short Name:
- J/ApJS/127/39
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present data on stellar and gaseous kinematics of 14 gas-rich early-type galaxies. File galaxies.dat contains the list of observed galaxies, with coordinates, distance, absolute magnitude, and position angles. File stellar.dat contains stellar rotation curves and velocity dispersion profiles. File gaseous.dat contains the gaseous velocity profiles.
- ID:
- ivo://CDS.VizieR/J/A+A/382/488
- Title:
- Stellar and ionized gas kinematics in NGC 2855
- Short Name:
- J/A+A/382/488
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present major and minor-axis kinematics of stars and ionized gas as well as narrow and broad-band surface photometry of the Sa spiral NGC 2855. In the nuclear regions of this unbarred and apparently undisturbed spiral galaxy the gas is rotating perpendicularly to the galaxy disk. We suggest that this kinematically-decoupled component is the signature of an acquisition process in the history of this galaxy.
- ID:
- ivo://CDS.VizieR/J/A+A/360/439
- Title:
- Stellar and ionized gas kinematics in NGC 4672
- Short Name:
- J/A+A/360/439
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report the case of the early-type disk galaxy NGC 4672 as a new example of a galaxy characterized by the orthogonal geometrical decoupling between bulge and disk. The morphological features of this galaxy are discussed as well as the velocity curves and velocity dispersion profiles of stars and ionized gas along both its major and minor axis. We conclude that NGC 4672 has structural (i.e. a bulge elongated perpendicularly to the disk) and kinematical (i.e. a stellar core rotating perpendicularly to the disk) properties similar to those of the Sa NGC 4698. The presence of the isolated core suggests that the disk component is the end result of the acquisition of external material in polar orbits around a pre-existing oblate spheroid as in the case of the ring component of AM 2020-504, the prototype of polar ring ellipticals.
- ID:
- ivo://CDS.VizieR/J/ApJ/809/25
- Title:
- Stellar and planet properties for K2 candidates
- Short Name:
- J/ApJ/809/25
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The extended Kepler mission, K2, is now providing photometry of new fields every three months in a search for transiting planets. In a recent study, Foreman-Mackey and collaborators presented a list of 36 planet candidates orbiting 31 stars in K2 Campaign 1. In this contribution, we present stellar and planetary properties for all systems. We combine ground-based seeing-limited survey data and adaptive optics imaging with an automated transit analysis scheme to validate 21 candidates as planets, 17 for the first time, and identify 6 candidates as likely false positives. Of particular interest is K2-18 (EPIC 201912552), a bright (K=8.9) M2.8 dwarf hosting a 2.23+/-0.25 R_{earth}_ planet with T_eq_=272+/-15 K and an orbital period of 33 days. We also present two new open-source software packages which enable this analysis. The first, isochrones, is a flexible tool for fitting theoretical stellar models to observational data to determine stellar properties using a nested sampling scheme to capture the multimodal nature of the posterior distributions of the physical parameters of stars that may plausibly be evolved. The second is vespa, a new general-purpose procedure to calculate false positive probabilities and statistically validate transiting exoplanets.